I have a Modcon Imperial forward fold. At about 80 to 100kph it has a shimmy which is felt through the seat of your pants in my FJ Cruiser. Feels exactly like the wheel balance is out on the rear tyres of the car but the car is perfect with the trailer removed. The only change I made was changing the rims to match the car, same height but slightly different offset so the tyres are slightly closer to the chassis. To rectify the problem I had the wheels balanced, changed tyres and wheels balanced again, trailer suspention/brakes/bearing/ alignment serviced by vehicle components (told them about the shimmy) all to no avail. Tried the trailer on three four wheel drives and it shakes them all. Moving the load around (forward/aft), changing the trailer hitch length, and pin height (DO35) also has little effect. Ball load changes from 130kg unloaded to 200kg loaded, also have no effect. Frustrated as we are trying to fix this before a two month trip away. Any suggestions? I could put the old wheels back on but that would require rechanging the studs and reverting to having one spare for each of the car and trailer instead of 2 matched spares. Thanks

Are the lug nuts the correct size? It seams as if the bolt holes in the rim are not the correct PCD to the hub, so the tapered heads on the lug nuts do not seat into the tapered holes properly. Have you tried having the rims balanced while on the trailer? Hope this helps.

The studs turned out to be OK. However, putting hubcentric spacer rings to centralise the FJ wheel on the trailer hub seems to have fixed the problem. The FJ shank nuts (not bevelled) don't seem to be good enough on their own to centralise the wheels on the trailer hub. The hubs on the FJ have a ring to centralise the wheel which are obviously absent on the trailer hub/drums.

MattP wrote:That's a very good point, I never thought of that.
I will check. Thanks very much!

robcaz wrote:Hi Matt,

Also if the wheel nuts are enclosed, they may be bottoming out on the studs before fully seating into the rim???